The present invention relates to a triple-fold type buckle for watch bands.
Japanese Utility Model Application Laid-open No. 3-101211 discloses a triple-fold type buckle. The buckle comprises a cover connected to one of the watch bands, a middle plate connected to the cover by a lateral pin, and a bottom plate connected to the middle plate by a lateral pin and to the other band. A casing having a pair of push plates is secured to the underside of the cover. The push plates are slidably mounted in the casing and a spring is provided between the push plates so as to urge the push plates outwardly. Each push plate has a manipulating portion projected from the cover through the casing, and a hook portion formed on an inner portion thereof so as to be projected from the casing. The middle plate has a pair of holes formed, corresponding to the hook portions of the push plates. The bottom plate has a pair of engaging projections to be engaged with the hook portions.
In order to couple the buckle, the cover and the middle plate are folded on the bottom plate so that the hook portions of the push plates are engaged with the engaging projections of the bottom plate through the holes of the middle plate. Thus, the cover is locked to the bottom plate. When disengaging the buckle, the manipulating portions of the push plates are pushed against the elastic force of the spring so that the hook portions are disengaged from the engaging projections.
However, when pushing the push plates in order to disengage the buckle, the user can not know whether the hook portions are entirely disengaged from the engaging projections. Accordingly, if the fingers pushing the push plates are released from the manipulating portions despite incomplete disengagement, the hook portions may be re-engaged with the engaging projections. Therefore, the cover must be forcibly opened by a finger under the condition that the push plates are pressed by other fingers.
Since the hook portions are projected from the underside of the cover to be engaged with engaging projections of the bottom plate and abutted on the middle plate when coupling, the thickness of the buckle is large.
Furthermore, since the holes must be formed on the middle plate, manufacturing process of the parts is complicated.